Cohesion and Coupling | Software Engineering
What is cohesion and coupling in software engineering ?
- Cohesion and Coupling both are very important concepts in software engineering . A Software design is said to be a good design by it's clean decomposition of modules and neat arrangement .
- A neat module or a software is said to be a good software if it contains high cohesion and low coupling .
- Cohesion can be defined as the functional strength of a module.
- Functional strength means how different functions and operation inside a perticular modules are connected with each other and whats the effect to another functions when any one or two function fails to perform .
- Coupling can be defined as the degree of interdependence or interaction betweeen two modules.
As you can see in the following image , cohesion is the functional strength of a module and where as coupling is the interdependance between two or more than two modules .
Types of Cohesion :-
There are basically 7 types of cohesion as follows -
- Coincidental cohesion
- Logical cohesion
- Temporal cohesion
- Procedural cohesion
- Communicational cohesion
- Sequential cohesion
- Functional cohesion
Let's see one by one each type of cohesion :-
1 - Coincidental Cohesion :
In this type of cohesions tasks are not related . That means the source codes are conceptually not related other than location of other codes . coincidental cohesion is one of the most worst type of cohesion.
2 - Logical Cohesion :
A module can be said as logical cohesive when all the functions performing similar type of operations like error handling , data processing etc.
3 - Temporal Cohesion :
A module is said to be performing temporal cohesion when all the functions inside a module are perform operations in same timespan .
4 - Procedural Cohesion :
A module is said to be performing procedural cohesion when set of functions of a module executing one after another .
5 - Communicational Cohesion :
When different functions of a module follows a same datastructure ( like array,stack ) for different operations like updation , insertion and deletion etc. then such modules are said to be communicationally cohessive.
6 - Sequential Cohesion :
A module is said to be sequentially cohessive when functions of a module executing sequentially,i.e, one functions output is working as an input to the another function .
7 - Functional Cohesion :
A module is said to be functionally cohessive where different functions of a module works / performs to achieve a single goal .
Now , Let's see what are the types of Coupling :-
Types of Coupling :-
There are basically 5 types of coupling available as follows :-
- Data Coupling
- Stamp Coupling
- Control Coupling
- Common Coupling
- Content Coupling
1 - Data Coupling :
When data of one module passed to another module as an input , then it's called data coupling.In this process , two or more than two modules communicates using an external data .
2 - Stamp Coupling :
If two modules communicates using composite data items such as record in pascal or a structure in c .
3 - Control Coupling :
If data from one module is used to direct the order of instruction execution in another , then it's called control coupling .
4 - Common Coupling :
If two or more than two modules sharing same global data then it's called common coupling ,because they are using common global data .
5 - Content Coupling :
Content Coupling exist between two module , if they shae code ,i.e; a jump from one module into the code of another module .
Difference between Cohesion and Couling
Cohesion :
- Defined as the functional - strength of a module .
- Shows relationship inside the module .
- You should aim for high cohesion .
Coupling :
- Dedined as intra-module binding .
- Shows relationship between modules .
- You should aim for low coupling.
Thank you for reading this article...
